I was just responding to parent who said > On the positive, the earth has been much warmer and much colder, and has had more carbon and less carbon in the atmo

I was just responding to parent who said > On the positive, the earth has been much warmer and much colder, and has had more carbon and less carbon in the atmosphere. the way I read it suggesting that it'll be fine. But it won't be, if co2 increased to 4000 ppm quickly enough, humans would not be fine. There were no humans during the time you were describing.